Switch



Dec. 12, 1933. J. A. SPENCER SWITCH Filed Sept. 5, 1930 2 Sheets-Sheet l Dec. 12, 1933. J SPENCER 1,939,285

SWITCH Filed Sept. 5, 1930 2 Shets-Sheet 2 Patented Dec. 12, 1933 OFFICE SWITCH John A. Spencer,

Newtonville, Masa, asaignor to General Plate Company, Attleboro, Masa, a corporation of Maasaehusetts' Application September 5, 1930. Serial No. 479,859

IClI-im.

This invention relates to switches, and with regard to certain more specific features, to snapacting or buckling switches, externally operated.

Among the several objects of the invention 6 may be noted the provision of a snap-acting or buckling switch, externally operated, which is adapted to function more effectively with thermostatic and like devices which normally operate through what is known as a creeping" range which ordinarily is detrimental to proper switch opening, but which with the present invention is turned to advantage so that the switch is in tighter contact under creeping conditions than otherwise; the provision of a switch of the class 18 described which is particularly adapted to be placed in combination with expansive thermostatic devices; and the provision of a switch of the class described which is simple and compact in arrangement, readily applicable to various designs and economical to manufacture. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts, which will be exemplified in the structure hereinafter described, and the scope of the application of which will be indicated in the following claim.

In the accompanying drawings,-ln which are illustrated several of various possible embodiments of the invention,

Fig. 1 is a side elevation showing the application of the invention, parts being broken away for clarity;

Fig. 2 is a cross Fig. 1;

Fig. 3 is an enlarged section showing the switch per se; i

Fig. 4'is a plan view taken from above the switch but on a smaller scale;

Fig. 5 is a diagrammatic view showing 9. normal closed position of the switch;

Fig. 6 is a view similar to Fig. 5 showing an incipient movement towards opening the switch;

Fig. 7 is a view similar to Fig. 5 showing full opening;

Fig. 8 is a view similar to Fig. 5 showing an incipient closing movement toward the Fig. 5

position;

Fig. 9 is a view similar to Fig. 1 showing an alternative form of linkage which may be used with the switch; and, Y

Fig. 10 is a diagram illustrating a phase, of construction.

Similar reference characters indicate corresection taken on line 2-2 of sponding parts the drawings.

Referring now more particularly to Fig. 1, there is illustrated at numeral 1 a base to which is screwed or otherwise fastened an expansive thermostatic element 3 to one end of which is fastened as shown at numeral 5 an interior, substantially non-expansive element 7. Expansive or contractive movement of the element 3, due to its changes in temperature has the effect of 35 moving the element '7 and, inasmuch as that element is substantially non-expansive, its movements do not serve to cancel or augment the movement provided by the element 3.

A second-class lever 9 (Fig. 1 only) is pivoted 9' at 11 on the base 1 and engages at knife edges 13 an adjustable head 15. The lever 9 reaches laterally to engage the head 1'7 of a switch pin 19 for purposes of imparting movement to said pin 19. A reaction spring 21 insures that the pin 19 is always forced against the lever 9. The lever 9 is provided with a safety lug 32 which prevents possible damaging action to the switch. Thisfeature will be clarified hereinafter.

The switch (Fig. 3) has been given the general throughout the several views of of line terminals 2'1, two of which are connected to a circuit 29 and separated at suitable intervals and adapted to be bridged by terminal engaging elements 31. Three terminal engaging elements are used for closing three gaps in order' to provide a series break. It will be such as shown at numeral 33.

The series of terminal engaging elements 31 indefinitely. Upon application of outside force, it assumes either of said two positions with snap action and maintains either position.

Centrally the disc 35 fits within a pair of collars 37 on the pin 19 and intermediate the center of the disc and its periphery openings 39 are provided fitting loosely about studs 41. The heads 43 of the stud 41 limit upward movement of the disc, the ,switch plate 25 being taken as a reference point. The length of the studs determines certain operating characteristics regarding temperature of opening of the switch, and, it is to 110 be understood that they may be made adjust-- able.

The switch pin 19 is reciprocable in a bushing 45, the latter being slotted as shown at 47 for 5 accommodating a cross pin 49, the purpose of which pin 49 is to permit reciprocation of, but prevent turning of the pin 19.

The action of the switch may be understood from Figs. 5 to 8. In Fig. 5 the switch is shown 1 in normal closed position, the terminal engaging element 31 being positioned against the line terminals 2'7. The disc 35 is arched and reacts against the head 43 of the stud 41, the normal spring of the same holding the elements 31 in 5 tight engagement. The switch pin 19 has been pushed up and is in indifferent position, so far as any pressure on the disc 35 is concerned. It

will be understood in connection with Figs. 5 to 8 that the two studs 41 are shown, one of them 20 being rotated from its 120 position for purposes of clarity. Actually the studs are positioned at 120. In Fig. 3 an added stud and an-added terminal engaging element has been shown in dotted lines, also for. purposes of clarity in describing the mechanics of the structure, although these would not ordinarily show in the cross section. 1

Returning to Figs.v 5 to 8, it will be seen from Fig. 6 that as the switch pin 19 travels downwardly, due to the combined action of the lever 9 and the spring 21, the upper one of the collars 3'1 pushes the center of the disc and tends to flatten it out or spread it, or provide a reverse curvature so that the center is directed to be driven through 86 the periphery. The disc leaves contact with the stud head 43 and the action of the pin 19 sets up a reaction at the terminal engaging elements 31 which is greater than the normal reaction existing in Fig. 5. Inasmuch as the position of the switch 40 pin 19 in Fig. 6 corresponds to a creeping position of the thermostat, it will be seen that under such conditions, instead of weakening the switch contact (as occurs in old types of thermostat) the contact are set tighter. That is to say,the incipient action or movement towards throwing the switch tightens the contact. At this stage of flattening of the disc, the terminal engaging elements 31 are wiped radially over their terminals so that clean circuit connections are maintained. These terminal engaging elements 31 function as fulcrums.

In Fig. 7 is shown the open position subsequent to-that of Fig. 6, wherein the center of the, disc has been driven through its periphery; and inasmuch as this involves an over-centering or buckling tendency, the switch snaps from the Fig. 6 to the Fig. 7 position. This snapping action results in the terminal engaging elements 31 being lifted from the terminals 27 and breaking the circuit,

66 the break being accompanied by the radial wiping action. This is done suddenly and effectively. The disc 35 at this time rests on the lower one of the collars 37. Referring to Fig. 3, it will be seen that a subsequent, secondary closure of the switch is prevented by a contact of the lower collar 3'7 with the bushing 45, even though the lever 9 be driven outwardly to an abnormal position. The bushing 45 being adjustable provides means for varying the initial set in the disc under closed 70 conditions thus making adjustable the time of snap action.

Finally, the Fig. 8 position is gone through upon re-closing the switch. In this event the lower collar 37 moves up and provides an action below '5 the center of the disc, the stud heads 43 providing areaction so that the center of the disc is driven. upwardly through. the periphery thereof. The next position after that of Fig. 8 is again the one shown in Fig. 5 wherein the disc is sprung upwardly causing an action at the head 43 for engendering the reaction at the line terminals 31.

Thus both opening and closing operations of the switch are exceedingly fast, whereby arcing is prevented. Also, creeping action of the thermostatic element is prevented from either slowly closing or slowly opening the switch. In the case of the opening event, the contact is actually incipiently tightened, rather than loosened as is ordinarily the case.

The length of the lug 32 on the arm 9 (Fig. 3) is such that it will touch the switch plate 25 prior to the pin 19 becoming positioned so as to damage the disc 35. Thus there is provided means for making suitable adjustments for effecting proper operation of the switch; and on the otherhand a safety device is provided for preventing excessive thermostatic action from-placing undue strain on the switch. The more rugged thermostatic linkage takes up such strain.

In Fig. 9 is shown how the switch may be connected inversely to that shown in Fig. 1 by interposing between it and the thermostatic elements 3, 7 a first-class lever 65, instead of a second-class lever. such as shown in Fig. 1. In this case a fixed knife edge fulcrum 67 is attached to a stud 69 fixedly held to plate 1. The action of the switch per se is the same, except that its response is in inverse order to the movements of the thermostatic elements.

It will be seen that adjustment of the knife edges 13 and/or 6'7 adjust the high critical temperatures and also the low criticaltemperatures at which the thermostats operate, this being in addition to the adjustments which are made at the time of manufacture of the studs 41 and the bushing 45., This does not interfere with the advantages gained by the switch in regard to increase in pressure and/or advancing action upon breaking contact.

A phase of construction is illustrated in Fig. 10 showing in somewhat exaggerated form how at the full open and closed" positions of the disc, its central portion is conical or biased with respect to the plane of the groove between the shoulders 37, thereby eliminating play between the parts in these positions. Intermediate these positions, and more particularly during snap action this bias vanishes, thereby permitting relative looseness which is highly desirable for best snap action.

By the term switch herein is meant a device for switching parts of any nature from one position to another and is not limited to electrical or mechanical devices per se.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in carrying out the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

In apparatus of the class described, a resilient, cupped disc, reciprocable means for applying movement to the center of said disc, an element controlled from the edge of said disc,-feaction means for the disc intermediate the center and a part adapted to be contacted by said element upon movement of the disc the fixed reaction means, said element eing separable by opposite snap action 0, said reaction means functioning in n with the reciprocable means upon reeof to cause reverse snapping of the disc 

